The splicers of this type generally comprise a lower dieplate, on which the strips to be joined together are placed end to end, a tape roll housing placed on one side of the dieplate at a generally right angle with it and from which a length of adhesive tape can be pulled across the joint area of the strip and pressed upon it to fasten said strips together in an end to end relationship. Generally such splicers are provided with blades to cut the tape flush with the edges of the strips once the adhesive tape has been applied and, if the splicers are intended for joining together perforated strips, they are also provided with a punching head to punch perforations into the applied tape, in register with the perforations of the underlying film strips.
The improved types of splicers carry two additional members, one at each side of the lower dieplate, whose tops project slightly over the plane of said dieplate. They run parallel to the dieplate edges, correspondingly to the joint area of the film. In such improved splicers, the adhesive tape is not applied directly on the strips, but stretched between these two members (which shall be termed "bridges" in the following) over the joint area but out of contact with it. Only after this operation has been performed, the adhesive tape is pressed against the joint area and simultaneously cut flush with the dieplate edges by an upper dieplate provided with blades to cut the adhesive tape and, where perforated strips are to be spliced, provided with punches to punch the necessary perforations through the tape.
The main advantages reaped by the provision of these two bridges are firstly the possibility of precisely correcting the position of the strips relatively to each other and to the tape prior to the application of the latter upon the splice area, and secondly that the tape, once applied will lie perfectly smooth and wrinkle-free on the splice.
After the tape has been cut, a piece or flap of it will remain projecting from the top of each bridge towards the dieplate, the length of each flap corresponding to the width of the gap intervening between the bridge top and the dieplate edge facing it. The flap adhering to that bridge which is interposed between the dieplate and the tape roll (to be termed "front bridge" in the following) remains attached to the tape drawn from the taperoll. The flap on the other bridge is discarded.
The gap between the front bridge and the dieplate edge must be sufficiently wide to permit an operator to insert his finger tip into it, in order to grip said flap, detach it from the bridge and pull it across the lower dieplate to stick it to the bridge located at the opposite side of the dieplate (which bridge shall be termed "rear bridge" in the following), preparatory for a successive splice.
On this flap there is clearly visible, in addition to the marks of the operators fingers, also the linear mark left upon its lower surface by the front bridge. Consequently, this flap cannot be used for a new splice and must be discarded. Therefore, the longer the flap, the more tape is wasted. Furthermore, the flap projects horizontally from the bridge or even bends down from it into the gap, thereby rendering the operation of gripping it extremely difficult. These difficulties are enhanced when such splicers are handled in a darkroom.
Another drawback of the known splicers arises from the tendency of the tape rolls to assume, with time, a cylindro-conical shape, with the external windings of the tape roll shifting axially outward. Such cylindro-conical taperolls become unusable for the splicer, as they can no more be kept aligned with the joint area.